Hummingbirds may seem like honest hovering fairies that trade pollination services for nectar, but more than 20 times, short-billed species evolved long toenails to cling, and some even pierce flowers to steal nectar instead, while long-billed species are forced to hover to feed. Free article by Colwell et al.: https://www.journals.uchicago.edu/doi/10.1086/726036 #hummingbird #pollination #nectar #beak